Structure and Kinetics of Micelles Based on Bottlebrush Block Copolymers in Selective Solvent
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We present structural and dynamic characterization of bottlebrush block copolymers in a selective solvent, where the backbone of the core block is tethered onto long fluoroalkyl pendent chains. Such bottlebrush block polymers readily self-assemble into spherical micelles with stretched cores, due to the increased chain stiffness of the bottlebrush core block. We examine the size of the core and corona within micelles scaled with the core block length, deviating from the classical theories based on Gaussian chains. In contrast, the fast relaxation of the bottlebrush core blocks enables the facile equilibration of the micelle formation. The kinetics of chain exchange between micelles is measured using time-resolved small-angle neutron scattering (TR-SANS), from which we find that the chain exchange among bottlebrush block copolymer micelles is tens of times faster than flexible block copolymer counterparts with similar activation energy.